The invention was conceived as a way of relating the Cartesian coordinate system to a person by visualizing the Cartesian coordinate system in relationship to a tennis court. Essentially the Cartesian coordinate system has four quadrants. The first quadrant is that portion of the coordinate system where values of x and y are both positive. The second quadrant of the Cartesian coordinate system is that area where the values x are negative and the values of y are positive. The third quadrant of the Cartesian coordinate system is where the values of x are negative and the values of y are negative and the fourth quadrant of the Cartesian coordinate system are where the values of x are positive and y is negative.
Probability is introduced into the instant invention by way of a number generator. Preferably the number generator is a pair of dice. Alternately the number generator may be a simple spinning wheel with numbers on it and the spinner or pointer will determine the number that is used. Obviously, the spinning wheel has no bias as the dice do. This will further help individuals understand the difference in probabilities.
U.S. Pat. No. 4,215,861 to Nemeth discloses an electronic tennis game which includes a microcomputer system which and when actuated by switches accepts inputs from those switches and processes those inputs according to a simulated tennis game to provide outputs in the form of the illuminated rectangular grids on the game board to indicate respective player and ball positions and to update the scoring displays. The '861 patent permits the players to select the longitudinal and latitudinal positions of the ball by means of a grid system labeled 1-16 across the top or x axis and 1-35 along the y axis. The selection of the positions in connection with the '861 patent are determined by a keyboard 60 as indicated in FIG. 1.
U.S. Pat. 3,949,992 to Battis discloses a tennis simulating table game which includes player-representing tokens that have different playing strengths and weaknesses designated on them. Transparencies overlie certain board sections and dice are used to develop numbers and there is a chart giving ranges of numbers that represent failure or success of the players in making the shots. The receiving player returns the ball in certain sections near him, fails if it is in other sections, and rolls the dice if it falls in still other sections. A player's chance of return depends on the dice values he rolls as related to the strength or weakness shown in his token. The '992 patent uses a combination of probability and a series of cards which indicate whether or not a shot is good or not good according to the player's rating.